Casing cutter apparatus



B. KRIEGEL CASING CUTTER APPARATUS A INVENTOR. wA/AeoK/EGEL,

BY Y QM llilrlfil l.

' Sept. 2o, 1949.

Filed June 5, 1945 Afro/@Vex Sept 20, 1949- v B. KRIEGEL 2,482,674-

cAsING CUTTER APPARATUS lFiled June 5, 1945 2 Sheejcs-Sheet 2 I Patented Sept. 2Q, 1949 UNITED STATES PATlzNTl OFFICE Bernard Kriegel, Los Angeles, Calif., assignor tok Baker Oil Tools, Inc., Vernon, Calif., a corporation of California Application June 5, 1945, Serial No. 597,627

l 18 Claims.

This invention relates to apparatus for cutting materials in a well bore, and is more specically directed to apparatus for cutting and milling casings, liners, and similar conduits while positioned in the well bore.

In the cutting and milling of casing and similar conduits positioned in a well hole, the peripheral cutting speed and downward feed or force of the rotating cutters against the casing for most eiiective operation can be predetermined, being dependent upon the casing size, its material and the type `of cutters employed. The cutters can be rotated at the proper speed, but difliculties are encountered in Vmaintaining constant the optimum downward feed or force of the cutter on the conduit. This is due to the inability of the driller to lower andimpose the proper weight of the drill string on the cutter, and to the force imposed on the cutting tool by the hydraulic :duid pumped down the drilling string for the purpose of iiushing the chips and other severed material from the cutting area for removal to the top of the well hole. Y

Accordingly, it is an object of the present invention to provide a cutter apparatus for use in a well bore in which a predetermined force is imposed on one or more cutters of the apparatus without regard to'the downward feed of the drill string or the hydraulic force of the fluid circulated down through the drill string.

A further object of the invention is to olset the eiiect of hydraulic forces tending to impose weight on one or more cutters operating in a well bore.

Another object of the invention is to utilize the pressure of the fluid pumped down a drill string to counterbalance or oiset the hydraulic effect of such fluid tending to force one or more cutters against the material operated upon.

Yet a further object ofthe inventionis to provide a cutting apparatus for operation in a well. bore in which A,the gravitational forceimposedon the apparatus cutter cany be completely or par" tially olset.

Still another object of the invention is to impose a predetermined gravitational force on cutters operating in a well bore independently of the weight of the drill strlngrextending tothe top of the well bore. Y

Another object of the invention is to provide a telescopic expansion joint for use in a well bore tubular string, in which the effect of the hydraulic.. force of the iluid within the joint is partly orfl entirely neutralized or counterbalanced to vThe invention has other objects that will become apparentv from a consideration of several of its embodiments -shown in the drawings accompanying and f orming part of the present specification. Theseembodiments will now be described inV detail, but it isto be understood that such detailed description is not to -be taken ina limited sense,-since the scope of the invention is best defined by the appended claims.

VReferring to the drawings:

Figure 1 is a side elevation of one form of apparatus in operative position within a well casing; v f

Figure 2 is a longitudinal section through the upper. part of the apparatus shown in Figure 1;

Figure 3 is a longitudinal section through the lower part of the apparatus shown in Figure l, forming a lower continuation of Figure 2;

Figure 4 is a view similar to Figures 2 and 3 of another embodiment of theinvention; and

I Figure 5 is a longitudinal section, on an enlarged scale, of the upper part of the apparatus illustrated in Figure 4.

i The cutting apparatus disclosed in the drawings is designed for operation in a well bore on the ylower end of aY stringvofrxdrill pipe or other tubing III. VIts lowerportion consists of a casing cutting and milling tool or underreamer Il, whose' body I2 is suitably secured to the driven member I3 of the upper expansion joint portion I4 ofthe apparatus, which has a driving member I5 attached to thefdrill pipe. The driving and driven members I5, I3 of the expansion joint areslidably splined to one ranother to form a telescopic driving connection for transmitting the rotary motion ofthe drill pipe I0 to the cutting tool YI I.y

The general type of cutting tool shown in the drawings for purposes ci illustration is disclosed and described indetail in United States Patent No. 1,857,616, granted May 10, 1932 for a Hydraulic underreamer. rIts main' body I2 preferably has a centering guide or pilot portion I6 at its lower end for centering the device in a casing or liner I'I. The body'is provided with an intermediate longitudinal slot I8 in which cutting blades I9 are pivotally mounted on a hinge pin 20 extending acrossv the slot. These blades are normally retained inwardly vof the slot within the coniines of the tool body, and are movable outwardly hydraulically by a mechanism including a plunger 2l having a piston 22 at its upper end reciprocable within a cylinder bore 23 in the body. Leakage along the exterior of the piston is prevented bythe Apiston rings 24 slidably engag.

ing the cylinder wall. A link 25 connects the plunger 2| with each of the cutter blades I9, the point of attachment between the lower ends of the links and the cutter blades being on the other side of the cutter pivot pin from which the cutting edges of the cutters are located, so that downward movement of the piston 22 and plunger 2l swings the cutter blades about their hinge pin 2t in opposite and* upward andL outward directions.

A helical spring 26 is disposed around the plunger 2l between the lower end of. thef piston and the bottom of the cylinder bore. The action of fluid under pressure against the piston 22 moves it downwardly against: the force: exertedi by the spring 26 whenever the cutter blades I9 are to be swung outwardly. Release of` this hydraulic pressure allows the spring to move the piston upwardly to its original position,.andin so doing elevates the plunger 2| to retract the cutter blades I9A oncemiore into.` the. transverse slotV i8 and within the confines of thetool body lil. Further details of. the operating mechanism of the particular tool inzquestion are'u-nnecessary to a proper understanding.v of: the. present vinvention and may be found in the patent abovereierred to. Y

Thercuttings.. removed1 by` the blades-I9 areV washed awayl from the. cutting region by the fluid circulating downthefdrill pipestring I and expansion joint 114 whichf` passes through the central passageway 2.11 the pistonY and' plunger and discharges from the oppositely directed oW beans 28 onto the cutting. blades ifi,` toscleanse them of cuttings-.andaushthez latterzupwardly to the top of the well bore... Thel restricted area through the plungerpassageway 2T and dowbeansV 28 causes aback' pressure.r to.y be. builtl up onI the upper side ofthe pistonf22 toi'shiftt the plunger downwardly against. the. fcrceof the spring 2B.

and urge the blades I9 outwardly against the casing Ii or wallof'the wellV bore. i

Each cutter when in its open and outwardly expanded position` has a l'ower cuttingr edge Illa designed to operate uporr the upper end I'Ia,A of the severed casing or liner section FT, for milling the casing or liner away upon* rotation of the cutting tool. Each bladev also has upperr and' outer cutting surfaces IiSU, I9c which together form an upper outer corner ld used for making the severing cut' in'the casing andV for locating casing couplings. The' forward portions' of` the bottom, outer and upper lcutting edges are all suitably hardfaced'. to increase theuseful life of the cutter and allow a substantial amount oi casing or other material to be removed from the well bore before the cutters become worn sufficiently to require' replacement.

Vlhen used for casingmilling. purposes, the apparatus is lowered in thewellcasing.` on the. end of the drill pipe string I0 until. an approximate location is reached. abovethepoint. at whichthe casing milling operation. is., to begin. During thislowering operation, the cutter blades. I9 are held in retracted positionby the springI 26.. Fluid is then circulated throughthe drill'v pipe for action under pressure uponthe piston 2-2, to move it downwardly and. swing the cutters |79 on their hinge pin 20 outwardly' until their upper outer corners ldv bearagainst the-wall ofthe casing. The drill string is-.then lowered gradually until these corners iSd expand outiintothe rst coupling space 29 reached", formed" by adjacent casing sections 3.01,. 3|: and; ther coupling y3.12 securing;

them together, which prevents further downward movement of the drilling string I0 and advises the operator that the desired location has been reached at which the severing cut is to be made and milling of the casing is to begin. It is to be understood that the severing cut could be made at points other than at a coupling.

liihile circulating fluiddown through the drill string IEI to impose hydraulic pressure on the piston 22 and exert an expanding force on the blades i9, the drill pipe string is rotated at the proper speed.` to rotate the cutting tool through Ythe expansion joint I4, and, in so doing, rotate the cutters i9 and force their upper and outer edges 'iii-ir- Ic, against the wall of the casing or coupling. Such upper and outer edges begin cutting away the casing, the fluid pressure acting downwardly on the piston 22 gradually feeding and expanding the cutters outwardly until the casing or coupling is completely severed. Rotation ofA the tool andl hydraulic forcing of its piston downwardly arecontinued until the upper edges I'fSboi the cutters haver cut upwardly and removedva suiiicientlength of collar 32 and casing 3i `as to be disposed in fully expanded. horizontal position, with the' cutters I9 engaging the upper end 68a of the longitudinal slot IB.' in the body I2; The cutting'apparatus and drill string can thenv be lowered to rest the lower cutting edges i911. of the cutters upon the upper end Ila. of the lower severed casing. section3l.. The drill pipeand casing. apparatus are rotated to move the cutters at the proper peripheral. speedaround the end I'Ia ofthe casing, and. a.downward force is. imposed on the .cutters I9 to mill away the casing for the required length.

For most effective operation of the cutting tool; itsl cutters should be rotatedv at the proper speedv and a denitedownward force imposed upon them continuouslyl during their engagement with: the severed end Ha of the casing, to: insure rapid removal of the casing material and maximum. life of the cutters themselves. It is dicult for thedr.ille r to control this weight from-the surface of the'wellj borefor many reasons, including the elasticity andspring-like action of the relatively long `string of drill pipe, and the' pulsations imposedT on. the drill pipe by the reciprocating pumps used'. inY pumping the circulating and washing fluidtheretllrough. A further. factor is also encountered. inthe nature of.v thehydraulic forces. acting. downwardly on the piston 22 and the cutter body I2 (or parts secured to it) after. the cutters: I9.` are expanded outwardly. to' their maximum. extent, which tend to exertadownward force on the cutter blades.

The present invention. avoids the above dif- -culties by incorporating an expansion joint I4 between the cutting tool" II and' they drill string Ill. This expansion joint, as shown in Figures 1 to. 3, inclusive,1includes. an: inner mandrel I5 threaded into a sub 33- securedto' the end of the drill pipe string I0, and an outer driven housing or barrel I3, telescopically receiving the mandrel I5, whose lower end: is threaded onto' a sub or adapter34 screwed intothe body I2 ofthe milling tool. The lower portion. of thev barrel I3 is provided with nternal driven splines 351 slidably engaged by' external. driving splines 3G on the lower part. of the inner mandrel I5. The outer barrel also comprises a relatively small diameter cylindrical member 31 threadedl onto the upper end of' the splined. portion. 3B. of. theA barrel,. which is threaded into,l arelatively large `diameter cylinder 39 having a head 40 screwed in itsupper end prof videdwith suitable sidesealslfl I Yfor making leak-- proof slidable engagement2 with the-upper end of the mandrel I5; Y f. Y

The mandrel I5 `has av relatively large diameter piston 42 carrying suitable opposed seals 43for slidable engagement with the wall of the large cylinder 39, and a lowerrelatively small diameter piston 44 carrying suitable .piston 'rings orseals 45 slidably engageable with the wall of the vsmall cylinder 3l. '.1

One or more ports 46 are formed through the mandrel I5 above the large piston 42 and below the cylinder head 46 to allow fluid under pressure to passv from the. central passage 41 in the mandrel into the annular cylinder space 48 between the upper large piston -42 and cylinder head 40. Bleeder. holes 49 areprovided atthe lower end of the large Ycylindergbetween'the upper and lower pistonsv42, l4tov allow fluid topass into and out ofthe cylinders between the pistons during telescopic movement of the mandrel I5 within theouter'barrel I3.

The combined weight of the outer barrel I3, lower sub 34, and cutting tool I'I is of a known amount, and is preferably such as to provide the required and most efficient downward cutting force on the lower edges I9a of the cutter blades I9 to effect most rapid removal of cutting material from' the casing, preferably through reducing the casing to relatively small chips that are easily washed away by the circulating iiuid passing down through the drill pipe string I6, expansion joint I4 and cutting tool II. In the event that this barrel, sub and cutting tool are insucient in weight, a suitable additionaltubular section of proper length and weight can be inserted between the expansion joint I4 and cutting tool II to provide the required total gravitational load on the cutters I9 urging them against the severed upper end I'Ia of the casing.

The splined or slidably keyed driving connection 35, 36 in the telescopic joint is suflicient in length to allow an adequate range of movement of the outer driven barrel I3 with respect to the inner mandrel I5. For example, a range of 18 inches to 36 inches could be provided. In operation, with the cutters I9 fully expanded and resting on the severed casing end I'Ia, the drill pipe string I is lowered to collapse the expansion joint I4 to its fullest extent, and is then elevated a short distance, such as an inch or two, to insure that the weight of drill pipe III is not imposed on the cutting apparatus I'I. The tubular string is then rotated at the prpper speed to rotate the cutting tool through'l the splined driving connection; andas thek cutters I9 mill away the casing, the force oi`-gravity gradually pulls the outer barrel I3 and cutting tool I I down with respect to the mandrel I and maintains the cutters I9 snugly in engagement with the severed end Ila of the casing, with the predetermined cutting or drilling weight'imposed on the cutters at all times. After a certain length of casing has been removed (but before the expansion joint I4 is extended fully), the drill pipe string I 6 is again lowered a short distance to again collapse the expansion joint I4, without imposing the weight of the former on the cutter apparatus II, and rotation continued to allow continued downward movement of the outer driven barrel I 3 and other parts olf the Yapparatus depending from it. Y

The telescopic joint I4 prevents the fluid circulated down through the drilljpipe string I0 6 fromv imposing a downward hydraulic force on thecutters "I9, which wouldY add` to vthe desired predetermined gravitationalfforce on the cutters providedby the weights kof the outer barrel I3, sub 34 and cutting tool I I themselves, and thereby subject the cuttersr to too great a cutting force or feed. The effect of this downward hydraulic force isicounteracted by creating an upwardly directed 'substantially equal hydraulic force. In the present instance, the annular area A of the cylinder space .48 between theupper' portion of the mandrel I5 and the wall of the upper cylinder 39 is 'equal to the area B across the lower portion of the barrel minus the area C through the pistonf22 and plungerV 2l orf the combined area throughY the liow beans 28, whichever is the lesser. By this arrangement the hydraulic pressure in the expansion joint 'I4 and cutter body I2 is caused' to be exerted through the mandrel ports 46 and inV an'upwardfdirectionon the outer barrel head or cylinder 'head'46 across theannular area lA. This same..lfiydrai'ilic force is alsofbeing exerted in a downward 'direction on the cutter apparatus across the area fB less the passage area .CthroughA the 'lpistonI 22; The downward hydraulic force on the cutting apparatus'is thus counterbalanced by an upward hydraulic force exerted onV the outer barrel I3. Re-v gardless of the pressure of'the hydraulic fluid circulated through the drillpipestring I0 and cutting apparatus,'it can have'no'effect in 'varyingor altering thepredetermined downward weightor gravitational pull imposed on the cutters I9, urging themagainst the upper severed end IIa of the casing. W

If'desired, thetareva'fof the" annular cylinder A can be made equal to the area B"by incorporating ow beans or nozzles `5Ilin the head equal in area to the areaofithe iiow beans 28 or passage 21 in the cutting* to'ol (whichever is the lesser); The iiuidentering the annular cylinder 48 through the mandrel ports'4l;` passes upwardly and yout through the flow beans or nozzles 50 in the'head to assist in washing the cuttings upwardly't'o the top of rthe' wellibore'. By making the annular area A'equal .to the area B,

a hydraulic balancecan be maintained at all timesregardless 'ofV changes in the area through the vcuttin'g'tool ow beans 28,'simp1y by using nozzles in the head whose passage area is equal tothe area of'such beans.

Ifdesi'red, 'some ofthe'dowrward weight of the outer barrel, sub and cutting tool can be removed from the Ycutters by making the area A 4greaterthan-th'e areaB. In this manner, a

lifting force is imposed hydraulically on the outer barrel vI3 andvcutting'rtool' II. Conversely, the

areaffAp can ib'e vdecreased 'with respect toY thev area B,-to stillallow downwardv imposition of hydraulic force "on" the cutters to a definite extent, asrequirements might dictate.

In the modification shown in 'Figures 4 and'5,`

the telescopic "joint VI4a between `the drill pipe string I0 and the cutting tool: I I :has been altered with respect to the'jont'shown in the other em- The areas and :the action.ohrdraulicffluid in.;

casacca? the expansionajointl are also proportioned in such" mann-er as tor neutralize or counteract the downward4 effectl of hydraulic force tendingk to imposeadditional weight on the cutters I9. In the present instance the inner driven mandrel 54 projects upwardly within the outer driving barrel l'v and has a lower relatively small diameter piston 55 in slidablesealing engagement with an internal flange 56 formed on the outer driving barrel. Suitable sideY seals 51 are mounted on the internal flange for slidable sealing engagement with the small extended piston 55 on the inner driven mandrel 54'. The outer driving barrel 5|l also has an upper internal flange 58 carrying one or more` seals 59 in'Y slidable engagement with the exterior of the upper portion 60 of the inner driven mandrel.

Between the internal flanges 56, 5B on thel driving barrel 5|', the mandrel 55 is provided with a relatively large diameter piston 6I carrying oneV or more seals 62 slidably engaging the wall of a cooperable barrel cylinder 63 extending betweenthe two internal anges 56, 58. An annular cylinder space 64 is formed between the exterior of the small piston 55 and the inner wall 63 of the barrel, having; an' annular area A1 which is equal to the pressure active area B1 across the inner driven*v mandrel 54 minus the area C of the flow beans 28. or passage 21. Fluid from the central mandrel passageway 65 enters the annular cylinder 64, through the mandrel ports 56 and exerts an upward hydraulic force on the large piston 615, counteracting the downward hydraulic force exerted on the mandrel' 54, sub 34a and cutting tool Il.

Bleeder ports 61 are. provided in the outer driving barrel' 5l between the upper end of the large piston 6| and the upper internal barrel flange 58 to facilitate telescopicv movement of the inner driven mandrel 545 with respect to the outer driving barrel 5I, by allowing free passage of fluid between the exterior'ofV the barrel and the space between the large piston 6 land the upper internal flange 58?, which varies in accordance with the telescopic movement of the mandrel and barrel.

It is, therefore, apparent that apparatus has been provided; in which the down weight imposed on the cutters can be predetermined by suitably selecting the weight of the cutting tool itself and the parts rigidly securedv thereto. Such cutters can be rotated to remove material from the well bore independently of theweight of the drill pipe string andv independently of the action of hydraulic; forces passing, through or imposed upon the apparatus; The invention Ahas other uses in addition to the milling away of casing sections. It can beV used in connection with cutters in a well bore performing underreaming operations, or' with bits for drilling the bore hole itself. Moreover, the expansion joint has general application in connection with well packers, for eX- ample. It permits ease of movement of the expansion joint, since the hydraulic forces are neither tending to extend nor contract the expansion joint. The proportioning and relationship of the area A or A1 to the area B or B1 can be such as to counterbalance the effect of hydraulic forces completely, as pointed out specically in describing the use of the device for milling out casing sections.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

I. Cutting apparatus adapted to be secured' to a tubular string `for operation in a well bore, including cutter` means, telescopic mea-ns atta'ched to said cuttermeansifor rotating the same upon rotation ofA said tubularA string, and means actingupcm said telescopic means to exert an upwardly directed force upon saidI cutter means while said, telescopic` means is in, collapsed position.

2. Cutting apparatus adapted for operation in a Ywell bore ron the'A end of a tubular string, including a cutting. tool, 'an telescopic joint secured to said cutting tool,4 andmeans within said telescopic joint for partially relieving said cutting tool of downwardly directed force imposed thereupon while said'. telescopic jointl is in collapsed position'.

3. CasingA milling apparatus'adapted for operation in awell, bore onthe. end. of a tubular string, including, cutter meanaia telescopicjoint having a driven member'attached: to said cutter means and a, driving member adapted for attachment to said tubular string, andmeans. responsive to the pressure of the. uid passing throughsaid tubular string and joint for exerting anr upward force on said driven member and its attached cutter means'.

e.. Casing: cutting: apparatus adapted for operation in la well: bore. through rotation ci a tubular string, including cutter means, a telescopic joint liavingV a driven. member attached to said cutter means and a driving: member adapted for attachment to saidtubular string, andl means responsive to the pressure of the fluid passing through saidl tubular str-ing and. joint for exerting an upward hydraulic force onv said driven member' 'and itsA attached cutter means to substantially 'oit-set the downward hydraulic force exerted by' such' fluidi on. said driven member and its attached: cutter means;

5. Casing' milling apparatusI adapted for .operation a well. bore, including cutter means, and

- a substantially' hydraulically balanced telescopic joint attached to` salda cutter' means.

6` Casing; milling apparatus adapted for' operation ina well bore. on the end: of a tubular string. including: cutterk means,A 'a telescopic joint comprising a driving member adapted' to be driveably connected to said' tubular string and a driven member in driving reiatiorr to said driving member andiadapted to be driveably connected to said cutter means, and. means responsive to the pressure of the flu-id .passing through said tubular string and joint f'or exerting an upward hydraulic force on` said driven: member 'and .its associated cutter'meansto substantially oiset the downward hydraulic force exerted by such fluid on said driven memberr andi itsVv associated 'cutter means.

7.. Cutting apparatus adapted for operation in awellbor'e on the-end'of 'a-tubular string, including cutter mean's 'a tubular driving member adaptedito be driv'e'ably connected to said tubular string, a tubular' driven! member keyed to said driving member 'slideabl'e telescopic relation therewith and' driveablyconnected to said cutter means', and: hydraulically operable means on said driven member responsive to the action of fluid passing through said members fer exerting an upward .forceo'n'said driven member and its asseciated cutter means;

8. Cutting apparatus adapted Ifor operation in a welll bore on the end ofv a tubular string, including cutter means, a driving member adapted to be driveably connected to said tubular string, a driven member'keyedto said driving member in slideable telescopic relation therewith and driveabi-y connected toi'said cutter means, said driving and driven members being spaced from one an- .9,- Ciliiing; erreaieladaridiof -Operioei a well bore on the end of a tubular string,'includ ing cutter means, a driving member adapted to be driveably connected to said tubular string, a driven member splined to said driving member in slideable telescopic relation therewith and driveably connected to said cutter means, said driving and driven members being spaced from one another to form an annular cylinder, means for feeding fluid from the interior of one of said members to said annular cylinder, and means secured to said driven member and adapted to be acted upon by the fluid within said cylinder.

10. Casing milling apparatus adapted for operation in a well bore on the end of a tubular string, including a cutting tool, a driving member adapted to be driveably connected to said tubular string, a driven member splined to said driving member in slideable telescopic relation therewith and driveably connected to said cutting tool, said driving and driven members being spaced from one another to form an annular cylinder, means for feeding fiuid from the interior of one of said members to said annular cylinder, means secured to said driven member and responsive to the pressure of the fluid within said cylinder for exerting an upward force on said driven member, the crosssectional area of said annular cylinder being such that the upward hydraulic force on said driven member is substantially equal to the downward force exerted by said fluid on the driven member and cutting tool.

11. Casing milling apparatus adapted for operation in a well bore on the end of a tubular string, including a cutting tool, a telescopic joint comprising an inner member adapted to be driveably connected to said tubular string and an outer member slideably splined to said inner member and driveably connected to said cutting tool, said inner and outer members being spaced from one another to form an annular cylinder, means for feeding fluid from th'e interior of said inner member to said annular cylinder, and means secured to said outer member and responsive to the pressure of the fluid within said cylinder for exerting an upward force on said outer member.

12. Casing milling apparatus adapted for operation in a well bore on the end of a tubular string, including a cutting tool, a telescopic joint comprising an outer member adapted to be driveably connected to said tubular string and an inner member slideably splined to said outer member and driveably connected to said cutting tool, said inner and outer members being spaced from one another to form an annular cylinder, means for feeding fluid from the interior of said inner member to said annular cylinder and means secured to said inner member and responsive to the pressure of the fluid within said cylinder for exerting an upward force on said inner member.

13. A tubular expansion joint adapted to be secured to a tubular string for operation in a well bore, comprising upper and lower members telescopically arranged in leakproof relation with respect to one another, said members being spaced from one another to form an annular cylinder, means for feeding fluid from the in- -terior offoi1e=of saidmembe'rssto sad'annular cylinder, and means secredto'saidilower member vand responsive .tcl-fthe pressure of the fluid within said cylinder for exerting an upward force on said lower memberr`v` Y 14.11A.. tubular @3.9211951991iointadapiedfio be secured to a tubular string v:for operationfin a well bore, comprising upper and lower members telescopically arranged in leakproof relation with respect to one another, means providing a cylinder space within one of said members, means for feeding fluid from the interior of one of said members to said cylinder space, and means secured to said lower member and responsive to the pressurel of the fluid within said cylinder Space for exerting an upward force on said lower member.

15. A tubular expansion joint adapted to be secured to a tubular string for operation in a well bore, comprising upper and lower members telescopically arranged in leakproof relation with respect to one another, means providing a cylinder space within one of said members, means for feeding fluid from the interior of one of said members to said cylinder space, means secured to said lower member and responsive to the pressure of the fluid within said cylinder space for exerting an upward force on said lower member, the pressure active surface on said lastmentioned means being such that the upward fluid force thereon substantially equals the downl ward force of the fluid on said lower member.

16. A tubular expansion joint adapted to be secured to a tubular string for operation in a well bore, comprising inner and outer members telescopically arranged in leakproof relation with respectl to one another, means providing an annular cylinder space between said members, means for feeding fluid from the interior of one of said members to said cylinder space, means Secured to one of said members and responsive to the pressure of the fluid within said cylinder space for exerting an upward force on said one member, the pressure active surface on said lastm'entioned means being such that the upward fluid force thereon substantially equals the downward force of the fluid on said one member.

17. A tubular expansion joint adapted to be secured to a tubular string for operation in a well bore, comprising inner and outer members telescopically arranged in leakproof relation with respect to one another, means providing an annular cylinder space between said members, means for feeding fluid from the interior of said inner member to said cylinder space, means secured to said outer member and responsive to the pressure of the fluid within said cylinder space for exerting an upward force on said outer member, the pressure active surface on said lastmentioned means being such that the upward uid force thereon substantially equals the downward force of the fluid on said outer member.

18. A tubular expansion joint adapted to be secured to a tubular string for operation in a well bore, comprising inner and outer members telescopically arranged in leakproof relation to one another, means providing an annular cylinder space between said members, means for feeding fluid from the interior of said inner member to said cylinder space, means secured to said inner member and responsive to the pressure of the fluid within said cylinder space for exerting an upward force on said inner member, the pressure active surface on said last-mentioned means being such that the upward fluid force thereon .i1 '12 Ysubsizaniziakhy equalsthe-downward 'force cf'the "STATES PATENTS u-id'on sad'mer member. y y

, A Numberv V Name Y' Date BERNARD KRIEGEL 1,805,515 Denny May 19, 1931 RFRENCES. CITED ,5 FQREIGN PATENTS The following 'refet'errics are of Vr'ccird in- Ithe Number Contry Date le of this paltht': 271,638 Germany Mar. 17, 1914 

